Proximity sensors are designed to detect the presence of nearby objects without physical contact. Optical proximity sensors utilize light sensitive elements to detect objects.
An optical proximity sensor includes an optical transmitter and an optical receiver. Optical proximity sensing is based on emitting light from the optical transmitter, capturing light reflected back to the optical receiver by a nearby object, and processing the reflected light to determine the proximity of the object to the sensor.
Optical proximity sensors are used in many applications, including mobile communications devices. For example, an optical proximity sensor may be used to determine when a mobile phone is held close to a user's face so as to turn off the mobile phone's display to conserve power.
A typical optical proximity sensor includes an enclosure assembly that is attached to a connector plate assembly that includes the optical transmitter and the optical receiver. As illustrated in FIGS. 1 and 2, the enclosure assembly 10 includes a package housing 12 formed with an optical transmit cavity 14 that is to receive the optical transmit element, and an optical receive cavity 16 that is to receive the optical receive element.
The package housing 12 has an optical transmit opening 24 extending therethrough to the optical transmit cavity 14, and an optical receive opening 26 extending therethrough to the optical receive cavity 16. Positioned within the respective cavities 14, 16 is an optical transmit element 34 and an optical receive element 36. Glue 40 is deposited within the respective cavities 14, 16 to hold the optical transmit and receive elements 34, 36 in place. The optical transmit and receive elements 34, 36 protect the optical transmitter and receiver, as well as filter undesired light.
As dimensions of optical proximity sensors are reduced, it becomes more difficult to dispense glue on the package housing 10 within the optical transmit cavity 14 and the optical receive cavity 16. This slows down the throughput of making optical proximity sensors. This problem is further compounded with a corresponding reduction in thickness of the optical transmit and receive elements 34, 36. Consequently, there is a need to address these concerns as the dimensions of optical proximity sensors are reduced.